Various measuring equipments such as a body composition meter, a thermometer, a body motion measuring device (pedometer, activity amount meter), or sphygmomanometer are conventionally known as a user equipment for acquiring the biological information, where a management system in which the measurement result of such measuring equipment is transmitted to a server to be collectively managed is known.
In such management system, management of the measurement result by a non-legitimate measuring equipment, which is not a legitimate article, having low reliability lowers the reliability of the system. Therefore, the management system includes an authentication system for authenticating that the measuring equipment is a legitimate article to eliminate the access by the non-legitimate measuring equipment.
In such authentication system, a method of encrypting the data for communication as described in patent document 1 is used to prevent the communication data for authentication from being analyzed and the authentication by the false authentication information created based on the analysis result from being carried out.
However, even if the communication data is encrypted, the communication data can be easily intercepted if the exchange of communication for authenticating the legitimate article becomes frequent such as constantly encrypting and performing authentication for every communication for transmitting the measurement result, and hence the authentication information becomes easily analyzed.
If a complex encryption is carried out in order to make the analysis of the intercepted communication data difficult, a considerable time is required for encryption with an equipment of low processing ability, and the communication time increases.
Therefore, it is not suited to applications of accumulating the biological information measured with various measuring equipments in the server.    Patent Document 1: Japanese Unexamined Patent Publication No. 9-139735